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THR rounds up all the major twists, new mysteries and more from this week in DC Comics TV shows.

Welcome to The Hollywood Reporter's weekly DC TV Watch, a rundown of all things DC Comics on TV. Every Friday, we round up the major twists, epic fights, new mysteries and anything else that goes down on The CW's Arrow, The Flash, Legends of Tomorrow and Supergirl andFox's Gotham and what it all means. Note: Arrow and Legends of Tomorrow did not air new episodes this week.

Supergirl

Cadmus makes its move: After months of mystery, Supergirl finally revealed what Lillian Luthor (Brenda Strong) is up to with Cadmus Labs. She kidnapped Mon-El (Chris Wood) to lure Kara (Melissa Benoist) to Cadmus so she could draw blood from the Kryptonian. She then gave that blood to Cyborg Superman — who the real Hank Henshaw (David Harewood) had become over the years after Cadmus experimented on him — and he used Kara's blood to trick the Fortress of Solitude into divulging secrets about something called Project Medusa, which will be revealed as an alien-killing virus. "Lillian's objective is to rid the Earth of what she sees as an invasive, infectious force, and that's the alien population," Strong tells THR. "In her mind, using Supergirl's blood to unlock the key to get the deadly Medusa virus, that's her way of manipulating science to fulfill her objective, to get rid of as many aliens as possible within a small region, including Supergirl. [Lillian] is more of a threat than people can possibly imagine."

The Luthor threat: While the obvious thing to do would be to label Lillian as a villain for everything she's done and will do with Cadmus, Strong believes there is more "grey area" than that to her character. "I don't think any villains sees themselves as a villain," Strong says. "She sees an opportunity to right a wrong and she sees an imminent threat that she perceives other people aren't fully aware of. She's got two vendettas: her personal vendetta and then trying to protect the world from what she sees as imminent doom. When you have someone who is that single-mindedly focused, you can definitely cast dispersions on their characters because there are blind spots in that commitment. She has this mama bear instinct to annihilate this threat or protect [her children and the world], so we're exploring that in a profoundly beautiful way."

Lillian and Lena: But since Lillian's daughter Lena Luthor (Katie McGrath) considers herself to be an ally and friend of Supergirl's, expect that to drive a wedge between the mother/daughter, even more so than ever before. "Lillian and Lena have been operating in their relationship at a slow simmer this entire time and the gas just got turned up, so whatever is boiling underneath, it's going to come to the surface in the next episode," Strong says. "You're going to see an explosiveness between the two of them. She's never been happy about any of her children being close to Supergirl or Superman [Tyler Hoechlin] since it will only end badly. She definitely will feel betrayed [by Lena working with Supergirl] and there's going to be major emotional aftermath from that."

Dad's big return: But the Luthors aren't the only ones dealing with parental issues, as Jeremiah Danvers (Dean Cain) finally reappeared in this week's episode at Cadmus Labs. He helped Kara and Mon-El escape, but stayed behind, promising that he'd be okay. "The big million-dollar question is what is he doing there? Is he a prisoner or is he involved with Cadmus? Or is he even running Cadmus?" Strong says. "No one really knows. In fact, I'm not really sure the actors know. I'm sure the writers know, but at this particular point in time, it has not been revealed to us. I can honestly say I have no idea."

Gotham

Civil war: Marvel isn't the only one with a civil war brewing, as DC Comics is setting up one of its own on TV between iconic Batman villains Oswald "Penguin" Cobblepot (Robin Lord Taylor) and Edward "Riddler" Nygma (Cory Michael Smith). While Gotham set up the potential between these two best friends to become more than friends when Penguin realized he had deeper feelings for Nygma, he made a grave mistake in killing Nygma's new girlfriend Isabella (Chelsea Spack) out of jealousy. He tried to cover up the murder, and for a while, Nygma believed that Butch (Drew Powell) was the culprit. He even captured and tortured Butch and Tabitha (Jessica Lucas) to get his revenge, but Butch didn't know the facts of how Isabella was murdered, tipping him off that he had the wrong person. Babs (Erin Richards), however, put it together immediately, figuring out that Penguin had feelings for Nygma, and it gave her the idea to set Nygma and Penguin against each other. With both of them out of the way, she'd be free to rule the criminal underworld of the city. But with the two most formidable and evil villains at war against each other, there's bound to be collateral damage. Who is going to suffer because of Babs' new plan?

The Flash

Alchemy unmasked: All the speculation surrounding who was under the Doctor Alchemy mask was true and completely predictable. Barry's (Grant Gustin) new coworker Julian (Tom Felton) was revealed to be Savitar's acolyte in this week's not-shocking episode. What was a surprise was how easily Julian convinced Barry to quit his job at the CCPD in exchange for Julian not telling the police that Caitlin (Danielle Panabaker) attacked him when her metahuman powers took over. Did Julian make Barry quit so he could continue his Doctor Alchemy activities without fear of getting caught, or did he truly just hate Barry so much that he didn't want to share an office with him anymore? And does Julian work for Savitar by choice, or is he being threatened to do Savitar's bidding? The way that he tried to resist hearing Savitar's voice at the end of the episode seemed to provide evidence that Julian isn't the most willing servant to the speed god, so perhaps there is more to this "twist" than meets the eye as of now. Seeing as how both fans and critics alike predicted Julian's double identity back when the character was first announced, one would think (and hope) that The Flash writers have more up their sleeve for this storyline.

What did you think of all the shocking twists, reveals and mysteries on the DC Comics shows this week? Let us know your thoughts in the comments section below.

Gotham airs Mondays at 8 p.m. on Fox; Supergirl airs Mondays at 8 p.m. on The CW; The Flash airs Tuesdays at 8 p.m. on The CW; Arrow airs Wednesdays at 8 p.m. on The CW; and Legends of Tomorrow airs Thursdays at 8 p.m. on The CW.